Advantage - dont have to worry about the oil pump failing which it will evenutally without a notice, also knowing you have a certain amount or premix of oil no matter what rpm or throttle you are at. on the stock oil pump it vary amount of oil that goes into your engine via throttle, the more throttle the more oil to your engine,

Disadvantage - none so far

To go premix, disable your oil pump and remove the cable on the carb wheel there is 2 cable running to the wheel one for the finger throttle and one for the oil pump or buy a block off plate and remove the oil pump, you gonna need to take out the pump and remove the coupler to stop the pump from pumping, some leave the pump in and most take the pump out, so they dont have hoses and cable laying around in the engine comparment... Also remember to empty out the oil sump if going to premix.

Ratio is the amount of oil to the amount of gas you have. Most people run a 40:1 ratio, I can't remember the ratio I use, but I put about 18oz of oil per 5 gallons of gas. Amsoil is the best, I use their dominator race oil. Yamalube from yamaha is also a great oil. Just stay away from the cheap 2 stroke oils that are meet to be used in outboard motors and you'll be find

Thanks so much for the info. Now I have to take off the exhaust to do all that? Remove oil pump and cables? What do I need to remove and how difficult is it?

It is usually the oil lines that crack or come off that lead to engine failures. The pumps are very reliable. The work you'd do to go back to the 1970's just check your lines instead and you should good. Pre-mixing is for weed wackers. Oil injection was invented to correct all the problems with premix:

1) Always too much oil unless you're at wide open throttle

2) Gumming up your carbs with the oil

3) Fouling spark plugs

4) Using more oil than you have to which equals $$ wasted

5) More pollution

I have been running 2 stroke PWCs with oil injection for many years and NEVER had one problem.

Yeah well go premix!! Just bought two 1200Rs last year checked lines and had them replaced and guess what I'm building two freaking motors right now!!!! It's not worth the what ifs just go premix and u don't have to worry..

Reputable nationwide known engine builders here on the forum even run premix on EFI skis where the orifice for fuel dispersion is even smaller, with no problems.

Running too fat of an oil mixture will lean out the fuel.
40:1 is recommended and has been proven. This eliminated fouling plugs as well.

Yes, a good working variable oil injection system works well, but premix is also an option just as the original poster is asking. Many powerful skis here on the forum run oil injection too.
Granted, the oil pumps rarely fail, it is the lines or cable that will tend to fail before the pump. Going premix eliminates three variables that can possible go wrong.

From a reliability standpoint, you can't beat premix.

Plenty of documentation here to prove, EFI, or CARB, premix will work well.